1. Field of the Invention
The present invention is related to mobile equipment with re-configurable transceiver and, in particular, to cognitive radio.
2. Description of the Prior Art
From mid-1980's, many researchers have hoped to realize a universal wireless communication system with 3 G communication techniques. However, in the past years, the universal wireless communication system is not realized. Further, to conform to different requirements (such as different data rates and different propagation distances) of actual applications, various new wireless communication standards have also been widely deployed in addition to 3G systems. Among so many wireless communication standards, some standards may co-exist in the same region or utilize the same frequency band. For instance, both Bluetooth and WiFi transmit data via the 2.4 GHz ISM band.
Although there are diverse standards, regulatory institutions in several countries found that most of the radio frequency spectrum was inefficiently utilized. For example, cellular network bands are overloaded in most parts of the world, but amateur radio and paging frequencies are not. To increase the overall utility of the radio frequency bands, mobile devices capable of operating conforming to multiple standards and in multiple bands are desired.
Unlicensed mobile access (UMA) is a telecommunication system allowing seamless roaming between local area networks and wide area networks using a dual-mode mobile phone. The local network may be provided based on private unlicensed spectrum technologies like Bluetooth or 802.11, while the wide network is alternatively GSM/GPRS or UMTS mobile services. This standard firstly introduces an international effort to allow multiple-standard multiple-band systems into realistic and ubiquitous wireless applications.
Software-defined radio (SDR) is considered as a means to facilitate the UMA concept. The basic idea of SDR is to adjust system parameters of a processor-based platform (usually facilitated by digital signal processors to execute physical layer transmitting/receiving functions), so that one platform can serve multiple system specifications.
Cognitive radio is an extended concept of SDR. More specifically, a cognitive radio is capable of sensing the communication environment (e.g. spectrum utility) so that the mobile device can self-organize appropriate communication and networking functions via re-configurable communication/network processors. With the potential of fully utilizing spectrum efficiency, cognitive radio has been considered as one key technology for future wireless communication and ubiquitous networking.
Up to this moment, most cognitive radio literatures deal with the conceptual design, tools, fundamental limits, or extremely complicated realization for military applications. Moreover, most of the research work is currently focusing on spectrum sensing cognitive radio, particularly in the TV bands. Under the concept of cognitive radio, unlicensed users are allowed to utilize licensed bands whenever it would not cause any interference (by avoiding them whenever legitimate user is sensed). The spectrum sensing cognitive radio first detects the unused spectrum, and then captures the best available spectrum to meet user communication requirements. For spectrum sensing cognitive radio, maintaining seamless communication and determining a fair spectrum schedule are both important issues.
Although spectrum sensing cognitive radio has provided considerable improvements in spectrum utility compared with prior arts, the full cognitive radio taking more communication parameters into account is still an essential development for future wireless communication. Therefore, in this invention, we would like to propose a complete architecture of terminal devices to realize cognitive radio that fits future commercial application scenarios and general convergence of Internet applications.